Chironomids as water quality indicators in the River Mignone (Central Italy)

Chironomids of the River Mignone (Central Italy) were studied in order to examine their community structure and their relationship to some common biological indices (Biotic Score, Extended Biotic Index, Indice Biotique de Qualité Générale) utilizing the total macroinvertebrate fauna (chironomids generally at family level) for water quality assessment in rivers.A total of 36 taxa belonging to Tanypodinae (2 taxa), Orthocladiinae (22 taxa) and Chironominae (12 taxa) was collected at seven stations four times during a year. The results support the importance of the chironomid identification in water quality assessment studies in rivers, and demonstrate the usefulness of the factorial correspondence analysis as ordination technique based on both qualitative and quantitative chironomid data to determine environmental quality gradients.The value as bioindicator of some taxa was discussed, and chironomid assemblages were related to biological water quality of the river according to functional feeding groups.This study forms part of a larger Research project supported by MPI and CNR grants and is aimed at the biological water quality assessment of the river and at the analysis of the total macrobenthic community.     

Fish Communities of the Lower Fraser River (Canada) and a 21-year Contrast

Fish communities were sampled at 14 sites along the lower 120km of the Fraser River, British Columbia by beach seine four times in 1972–1973 and three times in 1993–1994. Of the 37 species collected, peamouth chub, largescale sucker, starry flounder, and northern squawfish were predominant in either density or biomass. Densities and biomass of most species and all fish combined were higher in 1993–1994. Strong rank correlations of species abundance or biomass indicated that the overall fish community structure was very similar in both periods. At smaller spatial scales (reaches of 2–3 sites) and shorter time scales (by season), less than half the comparisons showed any significant correlation indicating changes in community composition. Largescale sucker, one of the largest contributors to biomass in both periods, showed decreased abundance, i.e., lower density, lower biomass, and large differences in the size-frequency distribution, specifically very low representation of small size classes. Other species, especially small-bodied forms, generally increased in numbers. Despite large changes in the lower Fraser River ecosystem in the past 21 years, the overall fish community has shown remarkably little change over that interval.     

Ciliated protozoa and water quality in the Parma River (Northern Italy): long-term changes in the community structure

Ciliated protozoans from sediments of the River Parma (Northern Italy) were collected from 7 stations, selected according to their hydrological, chemical, and physical characteristics, and to river zonation during autumn 1989. Fiftythree species were observed. A saprobic evaluation of the river was made using the taxocenoses observed, and the results were compared with data collected in 1978, when the River Parma still received untreated sewage. In 1989 the hilly section of the stream was found to be more polluted than in 1978, but in the plain section, the saprobic indices were now slightly lower. The marked change in the ciliate community of the hills was accompanied by an increase in organic load, which caused the disappearance of some typical species and dampened the diversifying effects of other environmental factors, producing comparatively similar community structures in that whole zone.     

Fish Communities of the Sacramento River Basin: Implications for Conservation of Native Fishes in the Central Valley, California

The associations of resident fish communities with environmental variables and stream condition were evaluated at representative sites within the Sacramento River Basin, California between 1996 and 1998 using multivariate ordination techniques and by calculating six fish community metrics. In addition, the results of the current study were compared with recent studies in the San Joaquin River drainage to provide a wider perspective of the condition of resident fish communities in the Central Valley of California as a whole. Within the Sacramento drainage, species distributions were correlated with elevational and substrate size gradients; however, the elevation of a sampling site was correlated with a suite of water-quality and habitat variables that are indicative of land use effects on physio-chemical stream parameters. Four fish community metrics – percentage of native fish, percentage of intolerant fish, number of tolerant species, and percentage of fish with external anomalies – were responsive to environmental quality. Comparisons between the current study and recent studies in the San Joaquin River drainage suggested that differences in water-management practices may have significant effects on native species fish community structure. Additionally, the results of the current study suggest that index of biotic integrity-type indices can be developed for the Sacramento River Basin and possibly the entire Central Valley, California. The protection of native fish communities in the Central Valley and other arid environments continues to be a conflict between human needs for water resources and the requirements of aquatic ecosystems; preservation of these ecosystems will require innovative management strategies.     

Macrobenthic community structure before, during, and after implementation of the Clean Water Act in the Neches River estuary (Texas)

Community structure of macrobenthos in the industrialized, tidal Neches River was studied 12 years after implementation of phase III of the Clean Water Act (CWA). Result were compared with a 1971–72 study conducted before implementation of the CWA and a 1984–85 study conducted after implementation of phases I & II of the CWA. The permitted BOD waste load decreased 93% between the 1971–72 and 1984–85 studies, then increased 19% between 1984–85 and the current study. A total of 50 taxa were collected during the 1971–72 study, 104 during the 1984–85 study, and 110 during the current study. Numbers of taxa per collection at each station increased by a factor of at least two between the 1971–72 and 1984–85 studies and were significantly different at the 0.0001 level. Numbers of taxa per collection at each station were not significantly different between the 1984–85 and the current study (p=0.286). Minimum collection densities in 1984–85 were higher than maximum densities in 1971–72 and were significantly different at the 0.0001 level. Collection densities were not significantly different between the 1984–85 study and the current study (p=0.374). Shannon's annual and station collection diversity values significantly increased (p=<0.05) between the 1971–72 and 1984–85 studies, but not between the 1984–85 and the current study (p=>0.05). Dendrograms of Sorenson's similarity index between all pairs of stations were more alike between the 1971–72 and the current study than between the 1984–85 and the current study. Evidence of some organic enrichment at the upper stations was indicated by the dominance of Limnodrilus hoffmeisteri and depressed oxygen concentrations. Environmental quality in the river has greatly improved since implementation of the CWA in 1972. Most of the improvments were due to phases I & II of the CWA, with little apparent change since implementation of phase III.     

Spatial and Temporal variations of mangrove fish assemblages in Martinique (French West Indies)

A study of the mangrove fish fauna in a bay of Martinique Island (French West Indies) was carried out at different seasons during two consecutive years. fishes were sampled with specific hoop-nets in the coastal areas at 8 stations.A total of 87 species was collected in the bay. Most individuals were represented by small-size specimens and juveniles. The overall species richness varied according to the stations and the sampling periods. The biomass and number of individuals were variable according to the location but remained stable in time. A factor correspondence analysis and a hierarchical clustering with median links were used to follow the evolution of the stations in space and time. Two types of stations were differentiated: the stations characterized by the mangrove and those under the influence of seagrass beds. A seasonal cycle, opposing the dry periods to the others, was observed.Thus, it seems that the use of the mangrove habitat by the fishes is optimized through a complete reorganization of communities in terms of species composition whereas the overall number and biomass remain stable. This model remains valid even for the most constraining biota of the mangrove ecosystem inhabited by a small number of well adapted species.     

Spatial structure of the caddisfly (Insecta,Trichoptera) communities in a river basin in NW Spain affected by coal mining

The changes in caddisfly community structure and composition in the Sil River basin (NW Spain), associated with a gradient in natural conditions and a succession of alterations induced by human activity (mainly urban wastes and coal mining), were studied. Twenty-nine Trichoptera taxa belonging to 11 families were collected. The community diversity analysis showed important spatial differences from source to mouth. Towns and, above all, coal mines produced an increase in sulphate and chloride concentrations and conductivity, which adversely affected the trichopteran assemblages. A stepwise regression model, which introduced sulphate and chloride as variables, explained the changes in diversity produced in the basin (r=0.837, p< 0.01). The lowest diversity and richness values were recorded in the rivers suffering the greatest impact from coal mining or urban wastes. The heterogeneity values of the communities for the main rivers were clearly different. The greatest community heterogeneity corresponded to the main axis of the basin and was explained by spatial variability in water chemical composition. No relation was detected between structural changes at spatial level and geographical distance, such that pollution processes basically controlled the dynamics of the Trichoptera communities. Partial-CCA using distance from the source as a covariable revealed alkalinity and urban and mining-derived pollution as the main factors influencing caddisfly distribution. However, an ordination of sites in relation to the corresponding vectors did not fully agree with the chemical characteristics of the water. The species composition of the Trichoptera communities, therefore, did not seem to be good indicators of the chemical features of the rivers. The structure of the community (as expressed by richness and the Shannon index) appeared to be the better indicator of pollution.     

Temporal and Spatial Distribution of Enterobius vermicularis (Nematoda: Oxyuridae) in the Prehistoric Americas

Investigations of Enterobius sp. infection in prehistory have produced a body of data that can be used to evaluate the geographic distribution of infection through time in the Americas. Regional variations in prevalence are evident. In North America, 119 pinworm positive samples were found in 1,112 samples from 28 sites with a prevalence of 10.7%. Almost all of the positive samples came from agricultural sites. From Brazil, 0 pinworm positive samples were found in 325 samples from 7 sites. For the Andes region, 22 pinworm positive samples were found in 411 samples from 26 sites for a prevalence of 5.3%. Detailed analyses of these data defined several trends. First, preagricultural sites less frequently show evidence of infection compared to agricultural populations. This is especially clear in the data from North America, but is also evident in the data from South America. Second, there is an apparent relationship between the commonality of pinworms in coprolites and the manner of constructing villages. These analyses show that ancient parasitism has substantial value in documenting the range of human behaviors that influence parasitic infections.     

Relationships Between Chemical Characteristics of Sediments and Macrofaunal Communities in the Cabras Lagoon (Western Mediterranean,Italy)

The Cabras lagoon is a large and shallow transitional system which periodically suffers from dystrophic events leading to massive losses of its biological resources. Excessive organic matter (OM) and sulphur compounds in sediments are often claimed to be major environmental co-factors triggering these events. However, still limited information is available on their relationships with benthic macrofaunal communities in coastal lagoons. In order to assess these relationships, we conducted monthly field investigations between 2001 and 2002, at three regularly-spaced stations set between the inlet and the mouth of the Cabras lagoon. Results showed reduced conditions of sediments, worsening during the warm season. This was consistent with very high OM contents, up to >‰20%, with annual means of 14–16%. Organic pollution-tolerant taxa, such as Tubificidae nc, Neanthes succinea and Polydora ciliata, dominated poor macrofaunal communities. Results of multivariate analysis indicated significant differences in both environmental variables and macrofaunal community structure and species composition between stations and through different periods. This study documented for the first time in a coastal lagoon that inorganic reduced sulphur pools (acid volatile sulphide and chromium reduced sulphur) of sediments are leading (‚best-matching’) environmental factors influencing the spatial and temporal distribution of macrofaunal abundance and biomass. We conclude that impoverished macrofaunal communities in the Cabras lagoon may show a slight recovery during winter–spring, but tend to regress to an early stage of faunal succession in late summer. We suggest that the combination of excessive amounts of sedimentary organic matter and high temperatures tends to lead to anoxic conditions especially in relatively deeper and more saline waters. These events may concur to periodic increase of production rates of toxic hydrogen sulphide in sediments, which rapidly diffuses to the water column with deleterious effects both on the benthic and pelagic components of the lagoon ecosystem.     

Spatial and temporal dynamics of the microbial community structure in the rhizosphere of cluster roots of white lupin (Lupinus albus L.)

White lupin was grown in a quartz sand–soil mix with poorly available Ca phosphate. The plants were harvested on days 21, 35 and 51 and DNA was extracted from the non-cluster roots, the young, mature and senescent cluster roots with adhering soil. Bacterial community structure was examined by PCR-DGGE of 16S rDNA, digitisation of the band patterns and multivariate analyses. In all root zones the bacterial community structure changed with plant age. The communities in the rhizosphere of the non-cluster roots were always different from those of the cluster roots. The bacterial communities of the cluster roots were cluster age and plant age dependent. The differences in bacterial community structure between the cluster root age classes were significant on days 35 and day 51 but not on d 21. A separate experiment, in which root exudates and samples for PCR-DGGE were collected simultaneously, showed that both bacterial and eukaryotic (18S rDNA) community structures change with organic acid exudation. While eukaryotic community structure of the cluster roots was correlated with citric acid exudation, bacterial community structure was correlated with cis-acconitic, citric and malic acid exudation.     

Periphyton (Aufwuchs) Communities of Ciliated Protozoa in Salt-Polluted Running Waters of the Weser River Basin — Their Structure and Indicator Value (Including Model Ecosystems)

The ciliates in aufwuchs communities on glass slides exposed to different amounts of salt pollution at several locations in the Weser River system were investigated. The results were compared with those from the study of model ecosystems exposed to salts. A comparison of the ciliate occurrence with a number of physical and chemical parameters showed that it is primarily the amount of salt present that determines which species are dominant. The number of species present decreases in the presence of high salt concentrations and in water flowing at a high velocity. A halobic index was formulated to indicate salt pollution quantitatively but turned out not to be useful due to the euryhaline potency of most of the ciliate species. The saprobic index can be used in rivers polluted with salt only if biological indicator species are present in sufficient number.     

Effects of flooding on recruitment and abundance of Golden Perch (Macquaria ambigua ambigua) in the lower River Murray

Flooding is often considered a stimulus for production of fish in floodplain rivers. In the southern Murray–Darling Basin (MDB), Australia, however, few native fish species have been shown to use the floodplain for spawning, and recruitment has been positively and negatively associated with flooding. In 2010/11, extensive flooding in the lower River Murray provided an opportunity to investigate the recruitment response of Golden Perch (Macquaria ambigua ambigua) following 10 years of drought and floodplain isolation. Annual variation in Golden Perch abundance and recruitment were investigated in anabranch and main channel habitats at Chowilla in the floodplain geomorphic region of the lower River Murray over a 7‐year period incorporating the flood and 6 years of in‐channel flow. Spatial variation in recruitment in the lower River Murray was also investigated by comparing the age structure of Golden Perch in the swamplands/lakes, gorge and floodplain geomorphic regions. Golden Perch abundance in the Chowilla region increased significantly postflooding compared with drought years. Age structures indicated that increased abundance was due predominantly to fish spawned during the flood (2010/11) and the previous year (2009/10), which was characterised by in‐channel flows. Age structure was similar in the nearby Katarapko Anabranch system indicating a uniform postflood recruitment response in the floodplain geomorphic region. Juvenile Golden Perch from the 2010/11 and 2009/10 cohorts were less apparent in the gorge and swamplands/lakes regions. Golden Perch have flexible life histories and will spawn and recruit in association with in‐channel rises in flow and overbank flows, but significant increases in abundance in the lower River Murray may result from overbank flooding. Contemporary approaches to flow restoration in the MDB emphasise overbank flows and floodplain processes. We suggest, however, that environmental flow management that incorporates floodplain and in‐channel processes, at appropriate spatio‐temporal scales, will result in more robust populations of Golden Perch.     

Lobomycosis in Bottlenose Dolphins (<Emphasis Type="Italic">Tursiops truncatus</Emphasis>) from the Indian River Lagoon,Florida: Estimation of Prevalence,Temporal Trends,and Spatial Distribution

Lobomycosis (lacaziosis) is a chronic fungal disease of the skin that affects only dolphins and humans. Previous studies have shown a high prevalence of lobomycosis in bottlenose dolphins (Tursiops truncatus) from the Indian River Lagoon, Florida (IRL). We studied the occurrence and distribution of lobomycosis in the IRL using photo-identification survey data collected between 1996 and 2006. Our objectives were to (1) determine the sensitivity and specificity of photo-identification for diagnosis of lobomycosis in free-ranging dolphins; (2) determine the spatial distribution of lobomycosis in the IRL; and (3) assess temporal patterns of occurrence. Photographs from 704 distinctly marked dolphins were reviewed for skin lesions compatible with lobomycosis. The presumptive diagnosis was validated by comparing the results of photographic analysis with physical examination and histologic examination of lesion biopsies in 102 dolphins captured and released during a health assessment and 3 stranded dolphins. Twelve of 16 confirmed cases were identified previously by photography, a sensitivity of 75%. Among 89 dolphins without disease, all 89 were considered negative, a specificity of 100%. The prevalence of lobomycosis estimated from photographic data was 6.8% (48/704). Spatial distribution was determined by dividing the IRL into six segments based on hydrodynamics and geographic features. The prevalence ranged from <1% in the Mosquito Lagoon to 16.9% in the south Indian River. The incidence of the disease did not increase during the study period, indicating that the disease is endemic, rather than emerging. In summary, photo-identification is a useful tool to monitor the course of individual and population health for this enigmatic disease.     

Distribution of the fish rotan (Perccottus glenii Dybowski, 1877) in the Irtysh River basin and analysis of possible consequences for environment and people

Since 1916, rotan (Perccottus glenii Dybowski, 1877) has widely distributed in northwestern Eurasia. In 1973–1976, rotan populations were first detected in the basin of the Irtysh River: in Lake Peschanoe (Mertvoe) of Chelyabinsk oblast in the basin of the Tobol, a tributary of the Irtysh. In 1975, this fish was introduced to one of the ponds of the city of Chelyabinsk. Analysis of the spatiotemporal dynamics of findings shows that earlier records of the fish correlate with the network of roads, and later findings, with the river network. The results of a special inspection of isolated and floodplain water bodies (n = 77) performed within Chelyabinsk, Kurgan, Omsk, and Tyumen oblasts in 2006 indicate that at present this unwanted invader occurs in the major part of the Tobol basin. The northernmost finding of this species is from the floodplain of the Tobol in the vicinity of Tobolsk, from the Karachino oxbow (58°02′N, 68°10′E). Rotan has also been found at the Irtysh headwaters as well as in the basins of its other tributaries: Ishim and Om. The expansion of rotan threatens the floodplain water bodies of the middle Irtysh. This species carries diseases, competes with other fish species for food, and actively eats young fish of these species. Therefore, the data on rotan distribution in the tributaries of the Irtysh should be taken into account when analyzing the dynamics of the fish community of this river. Biology of rotan assumes its influence on the functioning of the natural foci of opisthorchiasis.